US2025075A

US2025075A - Electron discharge device

Info

Publication number: US2025075A
Application number: US722706A
Authority: US
Inventors: Arthur L Samuel
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1934-04-27
Filing date: 1934-04-27
Publication date: 1935-12-24
Anticipated expiration: 1952-12-24

Description

Dec. 24, 1935. A. SAMUEL ELECTRON DISCHARGE DEVICE Filed April 2'7, 1954 INVEN TOR A. LSAMUEL mm @M ATTORNEY Patented Dec. 24, 1935 PATENT OFFICE ELECTRON DISCHARGE DEVICE Arthur L. Samuel, Orange, N. J assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., acorporation of New York Application April 2'7, 1934, Serial No. 722,706

'7 Claims. (01. 250-275) This invention relates to electron discharge devices and more particularly to such devices capable of generating oscillations of extremely low wave lengths, for example of the order of 30 centimeters or less.

In ultra-short Wave oscillators of the negative grid type, the upper limit of the frequency of oscillations generated is dependent in a large measure upon circuit resonance determined by the interelectrode capacities and the impedance of the leading-in conductors for the electrodes. -The impedance of the leading-in conductors is dependent primarily upon the dimensions of the conductors and their spacing relative to each other. The spacing of the conductors in turn is dependent upon the temperature to which the vessel in which the conductors are sealed may be heated safely.

One object of this invention is to decrease the impedance of the leading-in conductors for the electrodes in electron discharge devices in relation to the impedance of the electrodes.

Another object of this invention is to dissipate efficiently the heat from the electrode assemblies in electron discharge devices.

In one embodiment of this invention an electron discharge device comprises an enclosing vessel having a cathode, grid electrode, and anode supported therein by rods sealed directly in a wall of the enclosing vessel. The grid electrode and anode are provided with large surface heat radiating fins to which the grid and anode leading-in conductors are secured and which extend to immediately adjacent the wall of the enclosing vessel in which these conductors are sealed.

The fins also have secured thereto conductors each of which carries a metallic plate, the plates being disposed adjacent each other to form a condenser. These conductors and plates together with the electrodes define a tuned circuit. If desired, another condenser may be connected between the leading-in conductors for the grid and anode adjacent the points where these conductors are sealed in the enclosing vessel, the condensers, conductors and electrodes forming another tuned circuit within the enclosing vessel. This construction enables the close positioning of the elements forming the tuned circuits, and hence provides a low conductor impedance so that the device may be utilized to generate oscillations of extremely low wave lengths.

The invention and the features thereof will be understood more clearly and fully from the following detailed description With reference to the accompanying drawing in which:

Fig. 1 is a perspective view of an electron discharge device illustrative of one embodiment of the invention, portions of the enclosing vessel being broken away to show the electrode assembly more clearly; 5

Fig. 2 is an end view of the electrodes of the device shown in Fig. 1 showing the configuration and arrangement thereof;

Fig. 3 is a bottom view of the base of the enclosing vessel of the device illustrated in Fig. l 10 showing the arrangement of the electrode leading-in conductors; and

Fig. 4 is a perspective view of another embodiment of this invention.

Referring now to the drawing, the electron disl5 charge device shown in Fig. 1 comprises an enclosing vessel it having a base wall H from which a cathode, an anode, and a control electrode or grid are supported. The electrodes pref erably are positioned as closely together as is 20 mechanically and electrically feasible so that the electron transit times are small and the device may be operated at extremely high frequencies.

The cathode comprises a linear filament l2, which may be of thoriated tungsten, secured at 25 one end to a rigid bent wire or rod l3 sealed in the base wall H of the enclosing vessel. The filament is secured at its other end to a J-shaped flexible member or spring l4 carried by a rigid support or rod l5 sealed in the base wall ll ad- 30 jacent the periphery thereof.

The control electrode or grid comprises a pair of fins It to one edge of which a helical grid H is secured, as by Welding, the grid l1 being coaxially disposed about the filamentary cathode 35 I2. The fins l6, which preferably are of large area and hence radiate heat efficiently to maintain the grid at a safe operating temperature, are secured in a slot in a rigid metallic support or rod l8, sealed in the base wall ll of the en- 40 closing Vessel. Preferably, the fins extend to immediately adjacent the base wall as shown.

The anode comprises two metallic plates each including an arcuate portion I9 coaxial with the filamentary cathode l2, a flange 20, and an intermediate portion or fin 2|. The intermediate portions 2| are secured together in face to face relation by bent integral tabs 22 on one portion extending through apertures 23 in the other portion, and are fitted in a slot in a rigid metallic support or rod 24 sealed in the base wall I l of the enclosing vessel. The intermediate and flanged portions 2| and 20 respectively are of sufficient area to effectively cool the anode by radiation, and preferably extend to immediately ing vessel [0.

adjacent the base wall H, the intermediate portion being coplanar with the fins l5.

Inasmuch as the intermediate portions 2| of the anode and the fins l6 extend to immediately adjacent the base wall I l of the enclosing vessel, heat is radiated from the point of the base wall I! at which the rods l8 and 24 are sealed in the base wall. Hence the rods l8 and 24, which serve as leading-in conductors for the control electrode and anode, may be made very short and spaced close together so that the inductance thereof is small. Although positioning the rods l8 and 24 closely together increases the capacity therebetween, this is not detrimental for at very high frequencies, for example frequencies corresponding to wave lengths of the order of 30 centimeters or less, the inductance of the leading-in conductors constitutes the dominating factor in the impedance of the conductors. The rods l8 and 24 are made of relatively large diameter with respect to the distance between their axes so that the inductance of the rods per unit of length is small. At very high frequencies, the inductance of the rods is still of considerable magnitude and together with the capacity between the control electrode and anode assemblies provides a material portion of the tuned circuit in which the device is included.

By virtue of this construction, the surge impedance of the leading-in conductors may be made of the order of but two or three times the impedance of the electrodes whereby a relatively high operating efliciency for the device may be attained, and the device'may be operated at extremely high frequencies.

A metallic disc 3 I, having a getter material 40, such as magnesium, thereon, is supported from the rod or support l5 by a wire 32. During the fabrication of the device the magnesium may be vaporized to fix residual gases in the enclos- Mounted on the fins i6 is a metallic rod 25 having a slot for receiving the fins and disposed in alignment with the support or rod I 8. The rod 25 has secured to its free end a metallic plate having a semicircular portion 26 at right angles to the rod 25 and asubstantially rectangular plate portion 21 parallel to the rod. Similarly, a metallic rod 28 is mounted on the intermediate portions 2| of the anode and carries a metallic plate having a semicircular portion 29 coplanar with the portion 26 and a substantially rectangular portion 30 parallel to the portion 21. The

portions

21 and 30 form a condenser in series with the

rods

25 and 28, which serve as inductances, and together with the

rods

25 and 28 and the control electrode or grid and anode provide a tuned circuit within the enclosing vessel.

The resonant frequency of this circuit will, of

1 course, be determined by the capacity of the condenser formed by the plate portions 21 and 3D, the inductance of the

rods

25 and 28 and the capacity therebetween, and the capacity and inductance between the anode and control electrode or grid.

In another embodiment of this invention, two tuned circuits may be provided within the enclosing vessel l0. As shown in Fig. 4, illustrating this embodiment, the anode and control

electrode supporting members

33 and 34 respectively are substantially of the same length as the supports-or

rods

28 and 25 and carry

plate members

35 and 36 respectively having parallel spaced

portions

31 and 38 forming a condenser. The

supporting

members

33 and 34 and spaced

portions

31 and 38 are designed so as to form a circuit tuned to substantially the same frequency as the circiut including the supports or

rods

25 and 28. Preferably, these circuits are tuned to substantially the frequency at which the device is intended to be operated. The output circuit for the device may be a Lecher circuit including a looped member 39 adjacent the enclosing vessel and inductively coupled to one of the circuits within the enclosing vessel. For example, the looped member may be parallel to the

rods

25 and 28.

In this embodiment, the portions 01' the electrode supports extending through the wall of the enclosing vessel do not form a part of the oscillating circuits of the device. Hence, the conductors comprising the circuit may be made very short so that the device may be operated at extremely high frequencies, for example at frequencies corresponding to wave lengths of the order of 12 centimeters.

Although two specific embodiments of the invention have been shown and described, it will be understood of course that modifications may be made therein without departing from the scope and spirit of this invention as defined in the appended claims.

What is claimed is:

1. An electron discharge device comprising an enclosing vessel, a pair of parallel conductors sealed in one wall of said vessel closely adjacent each other, a control electrode havinga fin secured to one of said conductors and extending to immediately adjacent said wall, an anode having a fin disposed coplanar with said first fin, secured to the other of said conductors and extending to immediately adjacent said wall, a cathode, and leading-in conductors for said cathode sealed in said vessel at points remote from said parallel conductors. V p

2. An electron discharge device for the generation of ultra-high frequency oscillations, comprising an enclosing vessel housing a cathode, a control electrode, an anode, supporting members connected to said anode and control electrode at one end, inductive members individually secured to said control electrode and anode at the other end thereof, and plate members carried by said inductive members and spaced to form a condenser, said inductive members and condenser forming a turned circuit with said anode and control electrode tuned to the frequency at which the device is intended to oscillate. V

3. An electron discharge device comprising an enclosing vessel housing a cathode, an anode and a control electrode, and means within said vessel connecting said control electrode and anode and forming a plurality of tuned circuits therewith.

4. An electron discharge device comprising an enclosing vessel housing a cathode, an anode, and a control electrode, means within said vessel including a condenser electrically connecting said anode and control electrode at one end and forming a tuned circuit therewith, and means within said vessel including a condenser electrically connecting said anode and control electrode at the other end and forming another tuned circuit therewith.

5. An electron discharge device comprising a cathode, an anode, a control electrode, a pair of parallel conductive members individually connected to one end of said control electrode and anode, a condenser bridging said members, another pair of parallel conductive members disposed one in alignment with each of said first conductive members and individually connected to the other end of said control electrode and anode, said second members being of substantially the same length as said first members, and a condenser bridging said second members, said condensers having substantially the same capacity.

6. An electron discharge device comprising a cathode, a pair of parallel metallic supports, a control electrode and an anode individually mounted on said supports, plate members carried by said supports and spaced to form a condenser, a pair of metallic members extending from said control electrode and anode remote from said supports, each of said metallic members being longitudinally aligned with a corresponding one of said support members, and plates carried by said metallic members and spaced to form a condenser.

7. In combination, an electron discharge device for generating ultra-high frequency oscillations comprising an enclosing vessel housing a cathode, an anode and a control electrode, means within said vessel including a plurality of inductive members connecting said control electrode and anode and forming a plurality of tuned circuits therewith, and a conductor in juxtaposition to said enclosing vessel and inductively coupled to one of said inductive members.

ARTHUR L. SAMUEL.